Fix passthrough auth for users without a password

[howenyap]

Closes #373

Logic change

• when building a new Cluster with new_pool, pause the cluster if passthrough auth is enabled and password is empty
• on login, resume cluster if passthrough password exists

Testcases

Test	is AuthType::Trust?	is password empty?	cluster state
test_passthrough_empty_password_starts_paused	false	true	paused
test_passthrough_user_with_password_unpaused	false	false	not paused
test_passthrough_empty_password_trust_starts_unpaused	true	true	not paused

• test_replace_empty_password_cluster_with_passthrough_password

  • start with empty password, cluster should be paused
  • add new connection pool with passthrough password, cluster should resume

• test_pause_resume_toggles_all_pools: cluster.pause() should pause every pool, while cluster.resume() should resume every pool`

cargo nextest run --profile dev

bash integration/go/run.sh

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All committers have signed the CLA.

[codecov]

Codecov Report

❌ Patch coverage is 91.90476% with 17 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pgdog/src/backend/databases.rs	95.83%	7 Missing ⚠️
pgdog/src/backend/pool/connection/mod.rs	25.00%	6 Missing ⚠️
pgdog/src/frontend/client/mod.rs	0.00%	4 Missing ⚠️

📢 Thoughts on this report? Let us know!

[levkk]

Looks great! Quick ask, would you be able to add an integration test in integration/rust/src/auth.rs? You can create an additional [[users]] entry without a password in integration/users.toml and then try to connect to it from the integration test - just to confirm it works as expected.

Another thing, in client/mod.rs:

if passthrough_password.is_some() {
      conn.resume_cluster_pools();
}

While this is quick and pretty harmless, I think we should still check if the pool already has a password set, i.e., another client connected already and we configured the auth and resumed the pool. I think you can do this quickly by checking the Cluster struct for the password (we set it there, I believe).